-Dcom.sun.xml.ws.transport.http.client.HttpTransportPipe.dump=true
In Jdeveloper, the server startup command line is accessed from
Run Menu
Choose Active Run Configuration
Manage Run Configurations
Edit Default
Add the line to the end of the Java Options.
Also if you see a large work:WorkContext section in the SOAP header, you can remove that by adding this line to the startup.
-Dweblogic.wsee.workarea.skipWorkAreaHeader=true